cycle question

[DorySaid]

That is likely due to food nutrient buildup.
It likely hasn't fully cycled. But even if it went through the nitrogen cycle, you probably need another week or so to allow the nitrate and phosphate reducing bacteria to populate. I dont think they kicked in just yet, especially since you've recently seen a rise in nitrates not a reduction. Give it some more time maybe a week, then test again I would say. Probably not much point adding anymore food.
If after a week or week and a half, if the nitrates haven't gone done considerably, then consider some water changes over time.